1. Field of the Invention
The embodiments disclosed by this present invention relate to pixel binning of image signal processing, and more particularly, to an image signal processing method which refers to both an original color filter array image and a pixel binned color filter array image, and an associated device.
2. Description of the Prior Art
In image signal processing, the image quality of a color filter array (CFA) image is affected by photon noise, dark current noise and readout noise. To eliminate/reduce noise in the CFA image, often at least one de-noising process is executed in a Bayer domain or some other color space.
U.S. Pat. No. 8,295,631B2 discloses a pixel value technique in the Bayer color filter array which uses weighted means to adjust luminance and chrominance values according to the local edge response to eliminate noise. In a situation where the noise floor is unknown and line buffer resources are limited, the effects of the de-noising method are suppressed and may experience the side effects of distortion or vague images.
U.S. Pat. No. RE44482E1 discloses an active CMOS comprising a selection circuitry for selecting saved charge to achieve pixel binning, which can reduce the readout noise and the required exposure time. As the pixels are binned, however, the resolution of the image will be affected. A novel technique is therefore needed to overcome the problems of the prior art.